Reference is made to the following documents which are hereby incorporated herein by reference:
U.S. Pat. No. 2,251,330 - Fairbank PA1 U.S. Pat. No. 2,298,058 - Land PA1 U.S. Pat. No. 2,380,481 - Tillyer PA1 U.S. Pat. No. 2,565,362 - Eloranta PA1 U.S. Pat. No. 2,688,900 - Silverman PA1 U.S. Pat. No. 2,773,442 - Flynn et al. PA1 U.S. Pat. No. 3,838,913 - Schwarz PA1 U.S. Pat. No. 3,944,346 - Shindler PA1 U.S. Pat. No. 4,119,369 - Eloranta PA1 U.S. Pat. No. 4,264,154 - Petersen PA1 U.S. Pat. No. 4,386,832 - Nannini PA1 U.S. Pat. No. 4,595,262 - Ogle PA1 U.S. Pat. No. 4,943,152 - Whelen PA1 Polaroid, "Linear and Circular Polarizers To eliminate glare and enhance contrast for a variety of application . . . . in all industries"
The above-referenced patents illustrate a variety ophthalmic devices. For instance, Petersen, Eloranta (4,119,369), Eloranta (2,565,362), Tillyer, Fairbanks and Land are illustrative of sunglasses employing two overlying polarizers, one of which is rotatable relative to the other. The Eloranta, Tillyer, Fairbanks and Land patents illustrate such sunglasses wherein the user manually adjusts the rotational position of the movable polarizer; Petersen employs an electromagnetic acutater to rotate a polarizing element. The Polaroid brochure provides various commercially available sheet polarizers which are useful in the practice of this invention.
Sunglasses or goggles of the type having a frame provided with a bridge portion connecting right and left frame sections each supporting at least two polarizing lenses which are rotatable relative to one another (or wherein at least one is rotatable relative to another) to vary the intensity of the light transmitted to the wearer, and accordingly the color of the lenses, have several uses. Certainly it is desired to be able to vary the tint of sunglasses or goggles as the day progresses from moderate early morning light to the bright light of midday and then to moderate light as evening approaches.
For instance, the fisherman, sport or professional, begins his day before the sun has even risen and toils for his catch from early morning, when the sunlight is moderate, through midday when the sun is at its strongest. As the daylight differs, the fisherman may desire a different contrast during the day, especially against the water. Typical sunglasses may be too darkly tinted for the early morning; lightly tinted sunglasses may be too light for the midday sunlight. Thus, variable density sunglasses to meet the needs of the fisherman.
Consider further those who enjoy snow-skiing. Early in the day it may be best to have sunglasses or goggles of one tint for best contrast, e.g., to ski using a pinkish tint, but, later in the day, when the sun is strongly reflecting off the snow, it maybe best to have sunglasses or goggles of a different tint, e.g., to ski using a bluish tint, so as to then obtain the best contrast. Further, in the winter, the afternoon is shorter, with sunset occurring earlier in the day, such that a different tint may be desired towards the end of the day. Thus, variable density sunglasses or goggles to meet the skier's needs. However, when considering that snow-skiing is undertaken at such places as Aspen, Vail and other spots in Colorado, Lake Tahoe, Mont Treblanc, Quebec, Canada, the Alps, etc., for the skier, the variable density sunglasses or goggles should also be fashionable.
In addition, there are those who recreate on a beach. That is, consider the beach-goer. Not only does the sun vary from morning to sunset; but, there are those who sunbathe to watch their fellow sunbathers, as well as "be seen". For these folks variable density sunglasses are not only for meeting the need of the varying intensity of the sun during the course of the day; but also, for the purpose of making a fashion statement.
Likewise, consider simply a typical person who wears sunglasses on a typical day. In the morning he may wish one tint to simply reduce the glare of a mild morning sun; perhaps a darker tint at lunchtime when the sun is stronger; and, maybe a different tint as evening sets in, when this person is traveling or out in public for a social event.
Indeed, in this era of a depleted ozone layer, the need for shielding the eyes from UV light is rather important. In particular, excess short term ultraviolet light can cause photokeratitis, which is like a sunburned cornea. Long term excess ultraviolet light can contribute to cataracts or increase the risk of long term damage the central part of the retina. Thus, when the sun is at its strongest a person may desire yellow, orange, amber or a brown-tinted sunglasses, which can block out blue light, the next wavelength up from UV. Blue light contains more energy than the rest of the visible spectrum and can do damage akin to UV.
Sunglasses or goggles which change from light to dark automatically do not meet the needs of these individuals because they are typically slow to react, and do not adjust to the colors desired. Thus, in this era of automation, manually adjustable sunglasses or goggles may be desired; but this invention could include automated variable density sunglasses and is not necessarily limited to manually adjustable sunglasses.
Moreover, each of the above-mentioned individuals have further needs with respect to variable density sunglasses or goggles. As to the fisherman and beach-goer, the variable density sunglasses need to be substantially buoyant. For instance, in reeling in the "big-catch" or jumping for the Frisbee near the shoreline, sunglasses may fall off. If not substantially buoyant, the sunglasses may become Neptune's prize. Sunglasses can be rather expensive such that to lose them to the bottom of the sea can be a substantial loss. And, at the beach or, when fishing, the sunglasses may encounter water and the internal rotatable lenses should be substantially immune to this potential encounter.
As to the skier, the temperature gradient between the skier's skin or breath and the air can cause the sunglasses or goggles to fog. Thus, the sunglasses or goggles should preferably be substantially anti-fog. Further, the internal rotatable lenses, for the skier's use must be substantially immune to the potential of the glasses or goggles encountering snow.
And, for each of these wearers, including the typical person, if sunglasses containing more than one pair of lenses are to be commonly, fashionably worn, they must not only be attractive, but also be as easy to care for as sunglasses or goggles having one pair of lenses.
Thus, the adjustable or variable density sunglasses for each of these individuals needs to be substantially waterproof. For instance, to avoid the need of having to clean the interior polarized lenses. For example, to avoid the need of having to remove moisture, snow, dust, dirt, sand, salt or other particulate matter from the interior polarized lenses as well as to prevent corrosion of the polarized lenses.
None of the above-referenced patents teaches or suggests sealing the interior polarized lenses between a front frame component and a rear frame component so that the sunglasses or goggles are substantially waterproof, and/or substantially dust-proof, and/or substantially buoyant, and/or substantially anti-fog. Nor do these patents teach or suggest such sunglasses or goggles which may be fashionably worn.
Indeed, the teaching of these patents tends toward sunglasses or goggles which are not sealed, so that they can be disassembled for cleaning, i.e., the patents teach away from permanently substantially sealing (e.g., by sonic welding and glueing) the polarized lenses between front and rear frame components because such would not allow for easy disassembly. The problem of keeping the polarized lenses clean was dealt with by disassembly, and not by sealing the polarized lenses between front and rear frame components. Further, the goggles of the above-mentioned patents tend toward those which are for special purposes, and not for fashionable wear, e.g. skiwear. In addition, the present invention involves and exploits biorefringence, an effect which the sunglasses industry has avoided since the advent of polarized material.
Thus, heretofore a substantially hermetically sealed variable density ophthalmic device, e.g. sunglasses or goggles of the type having a frame provided with a bridge portion connecting right and left frame sections each supporting at least one rotatable polarizing lense or at least two rotatable polarizing lenses which are rotatable relative to one another or wherein at least one is rotatable relative to the other, have not been taught or suggested. Likewise, heretofore such hermetically sealed sunglasses or goggles which are substantially liquid-proof and/or substantially buoyant and/or substantially anti-fog have not been known or suggested.